For many years, paediatric cardiologists and paediatric cardiac surgeons have felt the need for a common diagnostic and therapeutic coding system with which to classify patients of all ages with congenital and acquired heart disease. This desire has been highlighted by the recent, and ongoing, enquiry into the outcome of paediatric cardiac surgery at the unit in Bristol, in the United Kingdom, and the resulting obligation to provide national and international comparisons of surgical results between centres caring for these patients. In order to incorporate effective clinical governance and best practice into our speciality, a method is required to gather accurate and validated data on the diagnosis, therapy and outcome of patients with heart disease from prenatal life through to adulthood. This would facilitate comparisons between individual units which fully take into account the mix of cases involved, and thus attempt to focus on the relevant and genuine factors underlying the differing outcomes in terms of both mortality and morbidity. For this to be achieved, it is essential to have a comprehensive system of coding and classification, using mutually exclusive and unambivalent terms. The system must be both easy to use, and fulfil the needs and expectations of widely different cultures of practice. Although many centres have developed their own system of internal audit, with their own coding system, and some co-operation has taken place between centres nationally and across international boundaries within Europe by the European Congenital Heart Surgeons Federation (see below), a cohesive, and comprehensive system suitable for setting standards has yet to emerge. Historically, this has partly been due to the lack of recognition by governments of the importance of such a process, with underfunding of initiatives aimed at addressing these issues, both technologically and in terms of human resources.